From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B929C54FD0 for ; Mon, 27 Apr 2020 04:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0996E206E2 for ; Mon, 27 Apr 2020 04:54:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="dH4og7eA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726460AbgD0Eyl (ORCPT ); Mon, 27 Apr 2020 00:54:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726231AbgD0Eyk (ORCPT ); Mon, 27 Apr 2020 00:54:40 -0400 Received: from mail-lf1-x144.google.com (mail-lf1-x144.google.com [IPv6:2a00:1450:4864:20::144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC7F5C061A0F for ; Sun, 26 Apr 2020 21:54:38 -0700 (PDT) Received: by mail-lf1-x144.google.com with SMTP id l11so12679303lfc.5 for ; Sun, 26 Apr 2020 21:54:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=uLhiyNXw2c6Bh3+KsgO2YOgoBrKeaIdCbQ6AiJEyQKg=; b=dH4og7eAlOMMU9zjR7c8eKMWiq0zQDIlb2GK5JUi+qJAjaTf4YedK6qxVckF97ctx5 bGBaeyT7ehGjDXEaCX92gHWiYMqnAUubFrHu0hoz3WspncTOpvQ4F7/X3w5wOVsoI7go OXVjRax5ecUCoM0aBlzesbwzg4KmPUA0ipv5jUruDQmbXTeukXf5y7WBtTNsWuktbExN /XjN09lzj1e0TaiFh00i48xhlkOurl0X8i6puThAwyi/YGCIm4Y0H4kAQYEoaAOxFWGL YCwosYJ1JgRriI9ryOukPusUIT40A/IGr0vxzU+K66172GMXmNKHyBsgNbhzUNW8XhYh kObA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uLhiyNXw2c6Bh3+KsgO2YOgoBrKeaIdCbQ6AiJEyQKg=; b=Hq7gTBiQgHiSQGV5bijQT+QoHOoa1aYsZU3DEn3/xxjF5pcVOHYQku5GE6QQxTDdHJ SLTeUqYb+gg0QYwxMgdFPSrB1soXe6DvYfeMJLuQU0F+6kqPwaaNb3D5nN+b1IunQgxT clzrk1l0WLSoZ1lJu+GnEkl6saT0Outi61dUq//XVz8YEXVdLxdzp741rUiwJKEZHQax SMEFxb+qPSJ1vY59yiYelffSyREEb9z+hbDq39jNCq1QI+RNqLFi5OU2dY/Ftns7om7M f1EY1g2WTzRForhwYN5Ryi/TSIH4RED7FSxM9Xc/6av5FqNRkSpBZSgEOsAtSHrIOQR8 F20g== X-Gm-Message-State: AGi0PuYtojCqWieySNPo4JTkd43zHWdvzbHjS5QN2aOWStnCgIrZeqyC UJJzbYq7mF9wofDkhvo1sOOID4R7QowsGMkYiEMYARi8 X-Google-Smtp-Source: APiQypLz3rHzGtlDr1/6paHraXe63+Mx5MbGFXQ94F/6yIUtpJZ84R5fG+aGZyp75Dsp1Qm7jipKQPY0eZUsNTZQuc0= X-Received: by 2002:ac2:5f63:: with SMTP id c3mr14190318lfc.15.1587963277244; Sun, 26 Apr 2020 21:54:37 -0700 (PDT) MIME-Version: 1.0 References: <1587726554-32018-1-git-send-email-sumit.garg@linaro.org> In-Reply-To: From: Sumit Garg Date: Mon, 27 Apr 2020 10:24:25 +0530 Message-ID: Subject: Re: [RFC Patch v1 0/4] arm64: Introduce new IPI as IPI_CALL_NMI_FUNC To: Doug Anderson Cc: Linux ARM , Catalin Marinas , Will Deacon , Thomas Gleixner , Jason Cooper , Marc Zyngier , julien.thierry.kdev@gmail.com, Daniel Thompson , Jason Wessel , kgdb-bugreport@lists.sourceforge.net, LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 25 Apr 2020 at 02:20, Doug Anderson wrote: > > Hi, > > On Fri, Apr 24, 2020 at 4:11 AM Sumit Garg wrote: > > > > With pseudo NMIs support available its possible to configure SGIs to be > > triggered as pseudo NMIs running in NMI context. And kernel features > > such as kgdb relies on NMI support to round up CPUs which are stuck in > > hard lockup state with interrupts disabled. > > > > This patch-set adds support for IPI_CALL_NMI_FUNC which can be triggered > > as a pseudo NMI which in turn is leveraged via kgdb to round up CPUs. > > > > After this patch-set we should be able to get a backtrace for a CPU > > stuck in HARDLOCKUP. Have a look at an example below from a testcase run > > on Developerbox: > > > > $ echo HARDLOCKUP > /sys/kernel/debug/provoke-crash/DIRECT > > > > # Enter kdb via Magic SysRq > > > > [11]kdb> btc > > btc: cpu status: Currently on cpu 11 > > Available cpus: 0-10(I), 11, 12(I), 13, 14-23(I) > > > > Stack traceback for pid 623 > > 0xffff00086a644600 623 622 1 13 R 0xffff00086a644fc0 bash > > CPU: 13 PID: 623 Comm: bash Not tainted 5.7.0-rc2 #27 > > Hardware name: Socionext SynQuacer E-series DeveloperBox, BIOS build #73 Apr 6 2020 > > Call trace: > > dump_backtrace+0x0/0x198 > > show_stack+0x18/0x28 > > dump_stack+0xb8/0x100 > > kgdb_cpu_enter+0x5c0/0x5f8 > > kgdb_nmicallback+0xa0/0xa8 > > handle_IPI+0x190/0x200 > > gic_handle_irq+0x2b8/0x2d8 > > el1_irq+0xcc/0x180 > > lkdtm_HARDLOCKUP+0x8/0x18 > > direct_entry+0x124/0x1c0 > > full_proxy_write+0x60/0xb0 > > __vfs_write+0x1c/0x48 > > vfs_write+0xe4/0x1d0 > > ksys_write+0x6c/0xf8 > > __arm64_sys_write+0x1c/0x28 > > el0_svc_common.constprop.0+0x74/0x1f0 > > do_el0_svc+0x24/0x90 > > el0_sync_handler+0x178/0x2b8 > > el0_sync+0x158/0x180 > > > > > > Looking forward to your comments/feedback. > > > > Sumit Garg (4): > > arm64: smp: Introduce a new IPI as IPI_CALL_NMI_FUNC > > irqchip/gic-v3: Add support to handle SGI as pseudo NMI > > irqchip/gic-v3: Enable arch specific IPI as pseudo NMI > > arm64: kgdb: Round up cpus using IPI_CALL_NMI_FUNC > > > > arch/arm64/include/asm/hardirq.h | 2 +- > > arch/arm64/include/asm/smp.h | 1 + > > arch/arm64/kernel/kgdb.c | 15 +++++++++++++++ > > arch/arm64/kernel/smp.c | 36 +++++++++++++++++++++++++++++++++++- > > drivers/irqchip/irq-gic-v3.c | 36 +++++++++++++++++++++++++++++++----- > > 5 files changed, 83 insertions(+), 7 deletions(-) > > This is amazing! > > * picked your patches back to my current 5.4 tree > * turned on "CONFIG_ARM64_PSEUDO_NMI" > * set the "irqchip.gicv3_pseudo_nmi=1" command line > > ...and bam I can trace on the locked up CPU instead of being left in the dark. > > I'm not sure I'm going to be too much use in actually doing the review > of the code since I'm not really an expert at how SGIs work (it took > me a while to realize that it must stand for software generated > interrupts) nor the bowels of the GIC. I tried to do what little > review I could. > > In any case, I'll keep this in my local patch stack for now and keep > testing it to make sure I don't notice any weird problems. Thanks for your review and testing. -Sumit > > -Doug From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32AEFC54FD0 for ; Mon, 27 Apr 2020 04:54:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0AC0B206B6 for ; Mon, 27 Apr 2020 04:54:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="TmEmS94L"; 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uLhiyNXw2c6Bh3+KsgO2YOgoBrKeaIdCbQ6AiJEyQKg=; b=clE31lm37QJkj9NdaxHAFk/LxqlOoHp4FAp6TAwWYoKfI5aHXTDg2c1Rv0tBJxNAp0 gwu7LZki659wUDAznS1OmFXrnQLLlZKc1yLTovGV2cvwDsJNZkfndNAy9YBOyp2yJMIU DnjjZzAJEYhs3Lhc32ptGTo9+FqgxLFC5ZZcI0itjjzZjIhypWpponywmoxkug1cEeFZ kPFrfFqV8dhoApLHcDP2e/wVTrCjLFwJAGlxZKvSwbLEgtnA0e5KIqZou2/CBvywoSyi BTVrmZQ+acUlvfXl7CPkO/jCMYGG52E31EYZiEQtKHH62ZPWn9HEzSROe4JUYjMC18VS wykQ== X-Gm-Message-State: AGi0PuaXkDQCjhIizcz81vELQusmUbnUqPXt7TGGUy2EqURjvv6aJCKi Nlg+54u05OS4JRJ0x8UMHnc390CzGRGcVkEX8nnrtg== X-Google-Smtp-Source: APiQypLz3rHzGtlDr1/6paHraXe63+Mx5MbGFXQ94F/6yIUtpJZ84R5fG+aGZyp75Dsp1Qm7jipKQPY0eZUsNTZQuc0= X-Received: by 2002:ac2:5f63:: with SMTP id c3mr14190318lfc.15.1587963277244; Sun, 26 Apr 2020 21:54:37 -0700 (PDT) MIME-Version: 1.0 References: <1587726554-32018-1-git-send-email-sumit.garg@linaro.org> In-Reply-To: From: Sumit Garg Date: Mon, 27 Apr 2020 10:24:25 +0530 Message-ID: Subject: Re: [RFC Patch v1 0/4] arm64: Introduce new IPI as IPI_CALL_NMI_FUNC To: Doug Anderson X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200426_215439_941194_AAB6E923 X-CRM114-Status: GOOD ( 24.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Thompson , Jason Cooper , Catalin Marinas , Jason Wessel , LKML , julien.thierry.kdev@gmail.com, Marc Zyngier , kgdb-bugreport@lists.sourceforge.net, Thomas Gleixner , Will Deacon , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, 25 Apr 2020 at 02:20, Doug Anderson wrote: > > Hi, > > On Fri, Apr 24, 2020 at 4:11 AM Sumit Garg wrote: > > > > With pseudo NMIs support available its possible to configure SGIs to be > > triggered as pseudo NMIs running in NMI context. And kernel features > > such as kgdb relies on NMI support to round up CPUs which are stuck in > > hard lockup state with interrupts disabled. > > > > This patch-set adds support for IPI_CALL_NMI_FUNC which can be triggered > > as a pseudo NMI which in turn is leveraged via kgdb to round up CPUs. > > > > After this patch-set we should be able to get a backtrace for a CPU > > stuck in HARDLOCKUP. Have a look at an example below from a testcase run > > on Developerbox: > > > > $ echo HARDLOCKUP > /sys/kernel/debug/provoke-crash/DIRECT > > > > # Enter kdb via Magic SysRq > > > > [11]kdb> btc > > btc: cpu status: Currently on cpu 11 > > Available cpus: 0-10(I), 11, 12(I), 13, 14-23(I) > > > > Stack traceback for pid 623 > > 0xffff00086a644600 623 622 1 13 R 0xffff00086a644fc0 bash > > CPU: 13 PID: 623 Comm: bash Not tainted 5.7.0-rc2 #27 > > Hardware name: Socionext SynQuacer E-series DeveloperBox, BIOS build #73 Apr 6 2020 > > Call trace: > > dump_backtrace+0x0/0x198 > > show_stack+0x18/0x28 > > dump_stack+0xb8/0x100 > > kgdb_cpu_enter+0x5c0/0x5f8 > > kgdb_nmicallback+0xa0/0xa8 > > handle_IPI+0x190/0x200 > > gic_handle_irq+0x2b8/0x2d8 > > el1_irq+0xcc/0x180 > > lkdtm_HARDLOCKUP+0x8/0x18 > > direct_entry+0x124/0x1c0 > > full_proxy_write+0x60/0xb0 > > __vfs_write+0x1c/0x48 > > vfs_write+0xe4/0x1d0 > > ksys_write+0x6c/0xf8 > > __arm64_sys_write+0x1c/0x28 > > el0_svc_common.constprop.0+0x74/0x1f0 > > do_el0_svc+0x24/0x90 > > el0_sync_handler+0x178/0x2b8 > > el0_sync+0x158/0x180 > > > > > > Looking forward to your comments/feedback. > > > > Sumit Garg (4): > > arm64: smp: Introduce a new IPI as IPI_CALL_NMI_FUNC > > irqchip/gic-v3: Add support to handle SGI as pseudo NMI > > irqchip/gic-v3: Enable arch specific IPI as pseudo NMI > > arm64: kgdb: Round up cpus using IPI_CALL_NMI_FUNC > > > > arch/arm64/include/asm/hardirq.h | 2 +- > > arch/arm64/include/asm/smp.h | 1 + > > arch/arm64/kernel/kgdb.c | 15 +++++++++++++++ > > arch/arm64/kernel/smp.c | 36 +++++++++++++++++++++++++++++++++++- > > drivers/irqchip/irq-gic-v3.c | 36 +++++++++++++++++++++++++++++++----- > > 5 files changed, 83 insertions(+), 7 deletions(-) > > This is amazing! > > * picked your patches back to my current 5.4 tree > * turned on "CONFIG_ARM64_PSEUDO_NMI" > * set the "irqchip.gicv3_pseudo_nmi=1" command line > > ...and bam I can trace on the locked up CPU instead of being left in the dark. > > I'm not sure I'm going to be too much use in actually doing the review > of the code since I'm not really an expert at how SGIs work (it took > me a while to realize that it must stand for software generated > interrupts) nor the bowels of the GIC. I tried to do what little > review I could. > > In any case, I'll keep this in my local patch stack for now and keep > testing it to make sure I don't notice any weird problems. Thanks for your review and testing. -Sumit > > -Doug _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel